Quassimarin compounds from the fruits of picrasma quassioides and their preparation and insecticidal use

Abstract

The present application relates to Brucea javanica bitterwood bitter compound and its preparation method and application, belong to natural medicine chemistry technical field, specifically related to two bitterwood bitter compound extracted and separated from Brucea javanica of Meliaceae Brucea javanica fruit (Brucea javanica), and the biomimetic synthesis method of compound 1, these compounds have good insecticidal activity.In addition, the preparation method of the present application is simple and easy to operate, the reproducibility is good, and the purity is high.

Description

Technical Field

[0001] This invention belongs to the field of natural product chemistry, specifically relating to novel skeletal quassinolide compounds prepared from the fruit of the plant Brucea javanica, their preparation methods, and the application of these compounds in the preparation of insecticides. Background Technology

[0002] Brucea javanica, a plant belonging to the genus Brucea in the family Simaroubaceae, has fruits and leaves that can be used medicinally. It possesses properties of clearing heat and drying dampness, killing parasites, detoxifying, stopping dysentery, and relieving malaria. It can be used to treat amoebic dysentery, malaria, and other diseases. Externally, it has a corrosive effect and is used for warts, corns, etc. Modern phytochemical and pharmacological studies have shown that Brucea javanica contains active ingredients such as quassinolide, alkaloids, and triterpenes, exhibiting various activities including antitumor, insecticidal, antiviral, anti-inflammatory, and antioxidant effects. Summary of the Invention

[0003] The purpose of this invention is to provide a novel skeletal quassin-like compound prepared from the fruit of *Brucea javanica*, its preparation method, biomimetic synthesis, and its application in insecticidal applications.

[0004] The structures of two novel skeletal basilidin compounds isolated from the fruit of *Brucea javanica*, a plant belonging to the genus *Brucea* of the family Simaroubaceae, are shown in the figure below:

[0005]

[0006] The preparation method of the present invention includes the following steps:

[0007] The dried fruit of Brucea javanica was extracted with ethanol, and the extracts were combined and concentrated to obtain an extract. The extract was extracted with dichloromethane and n-butanol, and the obtained components were subjected to silica gel column chromatography with isocratic gradient elution using a dichloromethanol system of 100:1-1:1. A total of 6 components Fr.AF were collected.

[0008] Using HP20 ODS column chromatography, fraction Fr.B was eluted with an ethanol-water system of 20:80-90:10 to obtain 6 fractions Fr.B1-B6.

[0009] Compounds 1-2 were obtained by elution with a petroleum ether-ethyl acetate system of 100:1-10:1 by silica gel column chromatography and separation by acetonitrile-water mobile phase in preparative reversed-phase high-performance liquid chromatography.

[0010] Preferably, the method for preparing the basilidin compound in the fruit of *Brucea javanica* uses the dried fruit of *Brucea javanica*, a plant belonging to the genus *Brucea* of the family Simaroubaceae.

[0011] Preferably, the method for preparing the quassin compound in the fruit of *Brucea javanica* involves extracting dried *Brucea javanica* fruit by reflux extraction with 70-80% industrial ethanol three times, each time for 2-3 hours.

[0012] Preferably, the method for preparing the quassinin compound from the fruit of *Brucea javanica* involves separating Fr.B4 using an acetonitrile-water mobile phase of 50:50-20:80.

[0013] This invention also provides a biomimetic synthesis method for a quassin-like compound 1 from the fruit of *Brucea javanica*. The biomimetic synthesis method involves rapidly synthesizing compound 1 using quassinol, which is abundant in *Brucea javanica*, as a precursor via a one-step Akdol aldol condensation reaction of an intercalation alkene.

[0014] Preferably, the biomimetic synthesis method includes the following steps:

[0015] The crotonic acid was dissolved in DMF under the following conditions: 0-20℃, with sodium hydroxide or potassium hydroxide as the catalyst, and a reaction time of 24-36 h. After the reaction was complete, it was quenched with 10% HCl, extracted with ethyl acetate, and the organic phases were combined and concentrated under reduced pressure. Then, the mixture was separated by preparative reversed-phase high-performance liquid chromatography using an acetonitrile-water mobile phase to obtain compound 1.

[0016] The results of systematic structural identification of the obtained compounds are as follows:

[0017] The structures of compounds 1-2 were identified using high-resolution mass spectrometry, one-dimensional NMR, two-dimensional NMR, computational NMR, computational ECD, and X-ray single-crystal diffraction. The corresponding structural characterization data are shown in Table 1, and the spectra are as follows. Figure 1-15 As shown.

[0018] Bruquass A(1): White amorphous powder; Via HRESIMS m / z 605.2590 [M+H] + (cacld for C 31 H 41 O 12 The molecular formula (605.2593) is determined to be C. 31 H 41 O 12 By analyzing bruquass A 1 HNMR, 13CNMR, HSQC, HMBC, and ECD spectra confirmed the structure of bruquass A, identifying it as a novel compound.

[0019] Bruquass B(2): White amorphous powder; Via HRESIMS m / z 607.2745 [M+H] + (cacld for C 31 H 43 O 12 The molecular formula (607.2749) is determined to be C. 31 H 43 O 12 ; By analyzing bruquass B 1 HNMR, 13 CNMR, HSQC, HMBC, and ECD spectra confirmed the structure of bruquass B, identifying it as a novel compound.

[0020] The present invention also provides a pharmaceutical composition comprising the above-described quassinoid compound prepared from Brucea javanica or its pharmaceutically acceptable salt and a pharmaceutically acceptable carrier or excipient.

[0021] The present invention also provides the use of the quassinoid compounds or their pharmaceutically acceptable salts, or pharmaceutical compositions containing the above compounds, prepared from the fruit of *Brucea javanica*, in the preparation of insecticides.

[0022] The insecticidal activity of the two novel skeletal compounds described in this invention was investigated. Compound 1 showed good antifeedant activity against diamondback moth, therefore, compound 1 described in this invention has the potential to be further developed into an insecticide.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The advantages of this invention are that all the compounds are new compounds with novel structures and optically pure compounds with defined stereoconfigurations. At the same time, they have good insecticidal activity and are worth further development.

[0025] Table 1. NMR data (DMSO-d6) for compounds 1 and 2

[0026] Attached Figure Description

[0027] Figure 1 HRESIMS spectrum of compound 1;

[0028] Figure 2 Compound 1 1 H NMR spectrum;

[0029] Figure 3 Compound 1 13 C-NMR spectrum;

[0030] Figure 4 HSQC spectrum of compound 1;

[0031] Figure 5 HMBC spectrum of compound 1;

[0032] Figure 6 Compound 1 1 H- 1 H COSY spectrum;

[0033] Figure 7 NOESY spectrum of compound 1;

[0034] Figure 8 HRESIMS spectrum of compound 2;

[0035] Figure 9 Compound 2 1 H NMR spectrum;

[0036] Figure 10 Compound 2 13 C-NMR spectrum;

[0037] Figure 11 HSQC spectrum of compound 2;

[0038] Figure 12 HMBC spectrum of compound 2;

[0039] Figure 13 Compound 2 1 H- 1 H COSY spectrum;

[0040] Figure 14 NOESY spectrum of compound 2;

[0041] Figure 15 Compounds 1 and 2 and their relationship with key HMBC 1 H- 1 H COSY and NOESY correlations and calculation of ECD spectra. Detailed Implementation

[0042] The embodiments listed below are intended to help those skilled in the art better understand the present invention, but do not limit the invention in any way.

[0043] Example 1: Preparation of compounds 1-2

[0044] The dried fruit of Brucea javanica was extracted with ethanol, and the extracts were combined and concentrated to obtain an extract. The extract was extracted with dichloromethane and n-butanol, and the obtained components were subjected to silica gel column chromatography with isocratic gradient elution using a dichloromethane system at 100:1, 50:1, 30:1, 10:1, 5:1, and 1:1. A total of 6 components, Fr.AF, were collected.

[0045] Using HP20, ODS column chromatography, fraction Fr.B was eluted with an ethanol-water system at gradients of 20:80, 40:60, 60:40, 80:20, and 90:10 to obtain six fractions Fr.B1-B6.

[0046] Compounds 1-2 were obtained by elution with a petroleum ether-ethyl acetate system at ratios of 100:1, 50:1, 30:1, 20:1, and 10:1 using silica gel column chromatography and by separation with an acetonitrile-water mobile phase in preparative reversed-phase high-performance liquid chromatography.

[0047] Example 2: Biomimetic Synthesis of Compound 1

[0048] Biologically, compound 1 is derived from the aldol condensation reaction of crocinol and isovaleraldehyde. Based on this, crocinol (50 mg, 0.10 mmol) was dissolved in DMF, and isovaleraldehyde (11 μl, 0.12 mmol, 1.2 equiv.) and sodium hydroxide (0.78 mg, 0.02 mmol, 0.2 equiv.) were added sequentially. The reaction was carried out at 0-20 °C for 24-36 hours. After the reaction was completed, the mixture was quenched with 10% hydrochloric acid, followed by extraction three times with ethyl acetate. The organic phases were combined and concentrated under reduced pressure to evaporate the solvent. The mixture was then separated by high-performance liquid chromatography to obtain target product 1, with a yield of approximately 16.9-25.3%.

[0049] Example 3: Investigation of the antifeedant activity of compounds 1-2

[0050] Prepare a 200 μg / mL solution. Use a perforator to punch 7 mm diameter leaf discs from the feeding leaves of the test insects. Immerse the leaf discs in different concentrations of the solution for 10-20 seconds, drain excess solution, and then lay them horizontally in a 9 cm petri dish lined with moisturizing filter paper. Allow them to air dry until the surface is dry. Inoculate each well with a certain number of test insects. Repeat each solution concentration three times. Seal the dish with plastic wrap and poke holes for ventilation. Use the drug solvent as a negative control and the commercial insecticide fipronil as a positive control. Place the petri dishes in an incubator at 26 ± 0.5℃, 50% relative humidity, and a L:D cycle of 16 h: 24 h. After 48 h, observe and record the number of dead test insects. A test insect is considered dead if it shows no reaction when lightly touched with a brush. Record the number of dead insects, the number of surviving insects, and the date of death. Calculate the mortality rate and corrected mortality rate.

[0051] Mortality rate = (Number of dead insects / Total number of insects treated) × 100%;

[0052] Corrected mortality rate = (treatment mortality rate - control mortality rate) / (1 - control mortality rate) × 100%.

[0053] Table 2. Insecticidal activity of compounds 1-2 against diamondback moth.

[0054]

[0055] The experimental results are shown in Table 2. The results indicate that compound 1 exhibits good insecticidal activity against diamondback moth at a concentration of 200 μg / mL, therefore, compound 1 described in this invention has the potential to be further developed into an insecticide.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A quassinin-like compound from the fruit of *Brucea javanica*, characterized in that, The compound has any of the following structures: 。 2. The quassinin-like compounds in the fruit of *Brucea javanica* according to claim 1, characterized in that, The croton seed mentioned is *Brucea javanica*, a plant belonging to the genus *Brucea* in the family Simaroubaceae. Bruceajavanica ].

3. The method for preparing the quassinin-like compounds from the fruit of *Brucea javanica* as described in claim 1, characterized in that, The compound is compound 1, and the preparation method is to rapidly synthesize compound 1 by reacting crotonol, which is abundant in Brucea javanica, with isovaleraldehyde via an aldol condensation reaction.

4. The preparation method according to claim 3, characterized in that, Includes the following steps: The crotonic acid was dissolved in DMF and reacted at 0-20℃ with sodium hydroxide or potassium hydroxide as the catalyst for 24-36 h. After the reaction was complete, it was quenched with 10% HCl, extracted with ethyl acetate, and the organic phases were combined and concentrated under reduced pressure. Then, the mixture was separated by preparative reversed-phase high-performance liquid chromatography using acetonitrile-water as the mobile phase to obtain compound 1.

5. A pharmaceutical composition, characterized in that, The pharmaceutical composition comprises a quassinoid compound from the fruit of *Brucea javanica* as described in claim 1 or claim 2, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier or excipient.

6. The use of the quassinin compounds or pharmaceutically acceptable salts thereof from the fruit of *Brucea javanica* as described in claim 1 or claim 2 in the preparation of an insecticide for diamondback moth.

7. The use of the pharmaceutical composition according to claim 5 in the preparation of a diamondback moth insecticide.

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